German intelligence had discovered the direction of nuclear research in the United States and Great Britain. The possibility of producing a massive atomic explosion was generally known and discussed, and calculations of a 'critical mass' were being made.

These emigres continued their research and discussions in the United States and in Britain.īy 1939 the thinking of nuclear scientists had progressed to such subjects as fission of uranium atoms and causing a chain reaction, particularly in the U235 isotope, when the material is bombarded by neutrons the comparative effectiveness of slow neutrons versus fast neutrons in achieving a chain reaction and the possible methods of separating U235 from U238 in natural uranium. Although not Jewish, Enrico Fermi had married a Jewish woman, and he feared and despised Mussolini's anti-Semitism. The emigres over the 1930s included Einstein, Theodore von Karman, John von Neumann, Eugene Wigner, Leo Szilard, Hans Bethe, Edward Teller, Lise Meitner, Enrico Fermi, and many others. German scientists who were Jews realized that the Nazis posed a deadly threat, and they began to emigrate, mostly to the United States. Hitler became Chancellor of Germany in 1933, and the Nazis began to abolish the civil rights of German Jews and to start their campaign of persecution. The early 1930s saw the rise of anti-Semitism in Germany and Russia. By the 1930s the nuclear scientists were exploring the revolutionary concept of splitting an atom of uranium with a neutron.

In 1908 Rutherford showed that the alpha particle was in fact an atom of helium in 1911 he announced that he had found the nucleus of an atom to be a minute but concentrated mass surrounded by electrons in orbits. Later, the 'nuclear group' was joined by Leo Szilard of Hungary, Otto Hahn of Germany, Michael Polenyi of Hungary, Walter Bothe of Germany, Lise Meitner of Austria, Hantaro Nagaoka of Japan, and others of similarly diverse backgrounds.īy the early 1900s these scientists were studying the structure of the atom and the deflection and scattering of alpha particles. Initially, these persons included well-known scientists such as Ernest Rutherford of New Zealand and Great Britain, Neils Bohr of Denmark, Pierre and Marie Curie of France, and Albert Einstein of Germany. The story of the atomic bomb started around the turn of the century when a small number of physicists began to think about, discuss, and publish papers about the phenomenon of radioactivity, the behavior of alpha particles, and the properties of various materials when irradiated.

Who invented the atomic bomb